Part 1 in this series discussed the common causes of forelimb lameness in juvenile dogs. Here I focus on the most common differential diagnoses for hindlimb lameness.

As discussed in Part 1, panosteitis and hypertrophic osteodystrophy can cause acute discomfort and lameness in the long bones of young dogs. However, both of these conditions tend to be self-limiting. Therefore, neither should be considered as the sole cause in a more persistent lameness. See Table 1 for an overview of assessing juvenile dogs exhibiting forelimb lameness.

Osteochondritis dissecans

Table 1: Keys to identifying the cause of lameness in juvenile dogs

Hindlimb lameness localized to the tarsal joint is most commonly caused by osteochondritis dissecans (OCD). Tarsal OCD has the same pathogenesis as OCD in general and most commonly affects large breeds (e.g., rottweilers, Labrador retrievers) younger than 1 year of age.

The clinical signs of tarsal OCD include lameness, joint effusion, medial thickening, crepitus, hyperextension with decreased flexion of the tarsocrural joint and pain on palpation.

Photo 1: A craniocaudal view of the tarsus demonstrating an OCD lesion on the medial aspect of the talus, resulting in the appearance of an increased joint space.

Radiographs demonstrate the typical tarsal OCD lesion on the medial condyle of the talus and concurrent osteoarthritic changes (Photo 1).

Treatment includes débridement of the free osteochondral fragment and underlying subchondral bone via an open arthrotomy. The joint space of the talocrural joint is generally too small even in large dogs to allow arthroscopic treatment.

Photo 2: A craniocaudal view of a stifle with a large OCD lesion on the medial aspect of the lateral femoral condyle.

The prognosis depends on the degree of arthritis present, but dogs often have continued progression of degenerative changes, thickened tarsi and intermittent lameness.

OCD can also affect the stifle joint, with radiographic changes noted as a flattening or divot on the medial aspect of the lateral femoral condyle (Photo 2). (Caution: Don't confuse the fossa of the long digital extensor tendon for an OCD lesion.) Often, disruption of the patellar fat pad by effusion is also noted.